This invention relates to imitation cheeses, such as cheddar, processed American, cream and mozzarella cheeses, wherein the caseinates are partially or totally replaced by pregelatinized starches which have been partially debranched by treatment with a starch debranching enzyme to yield a mixture of partially debranched amylopectin and short chain amylose, in addition to any amylopectin and long chain amylose which may be present in the untreated starch.
Amylose is a linear polymer of glucopyranosyl units, bonded by alpha-1,4-D-glucosidic linkages, which comprises one of the two types of polymers present in starch. Native starches also contain amylopectin, a branched polymer of short, linear alpha-1,4-D-glucosidic chains linked by alpha-6-D-glucosidic bonds at the branch points.
This invention also relates to imitation cheeses wherein the caseinates are replaced by starch which has been fully debranched by treatment with a starch debranching enzyme to yield short chain amylose, together with any long chain amylose which may be present in the untreated starch.
Early attempts to reduce cheese costs led to the development of cheese analogs in which vegetable fat replaced the more costly milk fat. Such analogs were usually manufactured by traditional methods from skim milk containing dispersed vegetable fats and were generally referred to as "filled" cheeses.
Later economic incentives and technical advances led to the development of fabricated cheese analogs manufactured from casein (milk protein) or its derivatives, vegetable fats or oils, salts, acids, and flavorings. Since casein derivatives are legally defined as non-dairy ingredients, the fabricated analogs were referred to as "imitation" cheeses.
Imitation cheeses include high-moisture content cheeses such as cream cheese, blue cheese and mozzarella, the latter accounting for a major portion of the casein-based imitation cheese market; medium-moisture cheeses, such as cheddar and provolone; low moisture cheeses, such as romano and parmesan; and pasteurized processed cheeses such as American cheese, cheese spreads and cheese products. These imitation cheeses provide the flavor and functionality of natural cheese at a reduced cost and, in addition, are lower in cholesterol since the animal fat has been replaced by vegetable fat.
Rennet casein, sodium, potassium, and calcium caseinates, and salts generated in situ by treating acid casein with the appropriate alkali, are used in the preparation of the imitation cheeses. All forms of casein useful herein are referred to as "caseinates". Besides providing a major protein source, the caseinates possess desirable setting, textural and emulsification properties, and their moderately low viscosity permits their use at high solids.
The high cost and uncertain availability of caseinates have been a major concern to food processors. For these reasons, the processors have been trying to find a readily available caseinate substitute, preferably a low cost substitute, to partially or totally replace the caseinates in imitation cheeses.
Substitutes for caseinates have included soy protein isolates, alfalfa protein, wheat gluten, starches, flours, corn syrup and mixtures thereof. The history of the use of such caseinate substitutes and methods for preparation of imitation cheeses are set forth in U.S. Pat. No. 4,499,116 issued Feb. 12, 1985 to Zwiercan et al. ("Zwiercan ,116") and in U.S. Pat. No. 4,695,475 issued Sept. 22, 1987 to Zwiercan et al. ("Zwiercan ,475") which are hereby incorporated by reference.
Certain starches have been successfully employed as caseinate replacers in imitation cheeses. The starches useful as caseinate replacers differ from starches and flours which have been used in various cheese products as thickeners, binders, and the like. Unlike the thickeners and binders, the caseinate replacement starches provide the texture, thermoreversibility (melt) and emulsification characteristics of caseinates in imitation cheeses. A starch characterized by thermoreversibility forms a gel when a cooked aqueous starch dispersion is cooled, which gel melts upon reheating and sets again upon cooling.
Zwiercan '116 discloses an imitation cheese wherein up to 80% of the caseinate is replaced by starches including pregelatinized converted starches (5-90 WF) (Water Fluidity) having an amylose content of at least 15% and no more than 40% and selected derivatives and crosslinked products thereof.
U.S. Pat. No. 4,608,265 issued Aug. 26, 1986 to Zwiercan et al. ("Zwiercan '265") discloses an imitation cheese, wherein 25 to 50% of the caseinate is replaced by pregelatinized modified high amylose starches, preferably converted and derivatized. The starch has an amylose content of at least 40% ("high amylose starch") and is preferably selected from the group consisting of derivatized starch, converted starch, converted and derivatized starch and crosslinked starch. The high amylose starch may be mixed with up to 80% by weight of a low amylose starch (less than 40% amylose). Zwiercan '475 discloses an imitation cheese wherein up to 100% of the caseinate is replaced by a pregelatinized, converted and derivatized high amylose starch.
High amylose starches are obtained from special hybrids of corn, barley and pea which contain as much as 70% amylose, and are more expensive and more difficult to isolate than the starches from more readily available sources such as corn, potato, wheat, rice, tapioca and the like. Most of the readily available starches contain less than 30% amylose.
In this invention, a starch containing a high percentage of short chain amylose is produced from any of the more readily available amylopectin-containing starches by treating the starch with an enzyme capable of cleaving the alpha-1,6-D-glucosidic linkages of the amylopectin. This enzymatic treatment cleaves the branch points on the amylopectin molecule, yielding a mixture of short chain amylose and partially debranched amylopectin, together with any remaining amylopectin or any long chain amylose present in the untreated starch.
In addition to providing functional properties similar to a high amylose starch (e.g., gel strength), this debranched starch mixture also improves the quality of the gel and melt properties of imitation cheeses. As a further advantage, for imitation cheeses wherein a label declaration for a modified starch (e.g., an ester derivative) is not desirable, but the functionality of the modified starch (e.g., thermoreversibility) is desirable, the debranched starches provide a "natural" alternative.
Thus, it is an object of this invention to provide functionally equivalent imitation cheeses wherein the caseinates are replaced by enzymatically debranched starches.